polychlorinated biphenyl (PCB) One of a range of compounds, first synthesized in 1881 and manufactured in 1929 and used mainly as liquid insulators in heavy-duty electrical transformers. They were detected in the environment in 1966 and associated with reduced reproduction in marine birds and mammals; they are also believed to compromise the immune system. Restrictions on their use were imposed in North America and Europe in the early 1970s, but they continue to cause contamination, because of their persistence and as a consequence of careless disposal of old equipment containing them.
polychlorinated biphenyl (PCB) Any of several stable mixtures – liquid, resinous or crystalline – of organic compounds. They are fire-resistant and are used as lubricants and heat-transfer fluids. The use of PCBs has been restricted since 1973 because they are toxic and their resistance to decomposition in streams and soils poses a threat to wildlife.
More From encyclopedia.com
Microbial Drug Resistance , Penicillin was the first antibiotic to be mass-produced for use in treating bacterial infections. Following its introduction during World War II (193… Dna Restriction Enzymes , Restriction enzymes are bacterial proteins that recognize specific DNA sequences and cut DNA at or near the recognition site. These enzymes are widel… Restriction Fragment Length Polymorphism , restriction fragment length polymorphism (RFLP) The occurrence of different cleavage sites for restriction enzymes in the DNA of different individual… resistivity , re·sis·tiv·i·ty / riˌzisˈtivətē/ • n. Physics a measure of the resisting power of a specified material to the flow of an electric current. resistivit… Restriction Enzyme , restriction enzyme (restriction endonuclease) A type of enzyme that can cleave molecules of foreign DNA at a particular site. Restriction enzymes are… Ohm , ohm / ōm/ • n. the SI unit of electrical resistance, expressing the resistance in a circuit transmitting a current of one ampere when subjected to a…
About this article
All Sources -
Updated Aug 24 2016 About encyclopedia.com content Print Topic